I am having problems with $.mobile.changePage.  After user submits a form and the credentials are verified I want to load another page.  I am trying to use $.mobile.changePage like this:

$.mobile.changePage("#index"); (this is in a js file).  The form is in a php file.

I get this error message:

TypeError: Result of expression '$.mobile' [undefined] is not an object.

I can't figure out what is going on. Can someone help me?

Thanks